Telephone call-bell



No Model.)

M. L. BAXTER.

Telephone Call Bell. No. 238,746. Patented March 8,1881.

UNITED STATES PATENT OEEicE,

MYRON L. BAXTER, OF AURORA, ILLINOIS.

TELEPHONE CALL-BELL.

SPECIFICATION forming part of Letters Patent No. 238,746, dated March 8,1881.

Application filed January 4, 1881. (No model.)

To all whom it may concern Be it known that I, MYRoN LESLIE BAX- TER, ofthe city of Aurora, county of Kane, and State of Illinois, have inventedcertain new and useful Improvements in Telephone Gall-Bells, of whichthe following is a specification.

The invention relates tolLi' call-bells upon a telephonic or other linethrough which electric currents may pass, and upon which line there arelocated two or more offices or subscribers; and its object is to enablea person at the end of such line, or at what is called a central office,to cause any particular bell to sound an alarm or call without ringingany other bell than the one intended.

Heretofore all the bells have been rung at the same time, the number ofstrokes indicatin g which office or subscriber was called or, as in somerecent improvements, synchronous movement of certain mechanisms atdiit'erent places has been called into play to render inoperative allthe bell-hammers on the line except one. The first method is highly0bjectionable, because each subscriber is obliged to give heed to allcalls, in order to know when his own is sounded, and because the almostcontinuous ringing of the bell is disagreeable to most persons untilafter they become so accustomed to it as to disregard not only the callsof other subscribers, but their own as well. In private residences thisis particularly annoying. The other method is found to be impracticable,because it has been necessary to use at leasttwo strengths of current--the weaker to move the parts into position and the stronger to sound thebells. As a line is liable to great variation in its condition asregards resistance and insulation, a weak current to-day becomes astrong one to-morrow, and vice versa.

The object of my invention is to provide a means whereby any particularbell may be rung to the exclusion of all the others by the use of onestrong current without modification as to strength or direction.

The invention consists in arranging at each station an electro-magnetoperated by the current on the main line, and which actuates astep-by-step movement, such as is employed in the ordinary dialtelegraph-instrument, a

shunting electro-magnet which is worked by a local battery (thetransmitter-battery) when a certain tooth in the escape-wheel makesconnection, and a continuous-ringing bell which is shunted into the saidlocal circuit whenever the shunt-magnet is allowed time to fully actuateits armature.

The essential part of my invention consists of so retarding the actionof this shuntingmagnet that it may at any time be briefly acted upon bythe local battery without causing the bell to ring.

The accompanying drawing shows the arrangement at one station, and allothers are the same.

Though the invention is susceptible of bein g used upon either an openor closed circuit, it is here shown and described in use on aclosed-circuit line.

In the drawing the main line is shown passing through the office andconnected with the electro-lnagnet A. B and 0 form the step-bystepmovement, the ratchet or escape wheel 0 and the anchor B being made ofnon-conducting material, except teeth 0 and prong b, which, when inconnection, make complete the electric circuit from the local battery Dthrough d E c H Ff to the escapement.

E is the shunt-magnet which actuates the armature K and beam 0 g,pivoted at c.

L is a cylindrical vessel open at the top and filled nearly full ofglycerine or other suitable liquid.

M is a piston fitting loosely in L, and attached by its rod to the endof the beam 6 g.

0 is the bell-magnet, n the bell-hammer, and Q is the bell proper,(indicated by the dotted lines.)

The operation of the devices herein described, when applied to a line,is as follows: The operator at the central ot'fice, by sending currentsof electricity intermittently through the line, causes all theescape-wheels to advance or revolve synchronously, one tooth for eachimpulse so sent,aud at each step some one metal tooth is in contact withits metal prong; but at no two stations are the contacts established atthe same step. This is an old, well-known device, and I do not claim itas my invention. I only claim to make it practically useful by employingthe maximum current to operate it.

Whenever a contact is made the current from the local battery is sentthrough the helix E, and the armature K, with its beam 6 g, commences todescend; but as it must force down the piston M in the cylinder L, itsmotion is retarded, because the glycerine or other suitable liquid mustbe transferred from the lower to the upper portion of the cylinder,passing through a very contracted passage around the piston. The passageis, however, wide enough to allow the piston to move easily if movedslowly. If, now, it is not desired to call that particular office,another step of the escapement breaks the circuit of the battery D, andthe spring N slowly restores the beam 0 g to its normal position but ifit is intended to call the station in question, the contact is kept upuntil the beam 0 g has completed its stroke, when the bell-magnetO willhave been shunted into circuit and the short line F f cut out, for asthe beam descends it makes contact between the spring I and the screw G,and immediately thereafter breaks contact between the spring H and thescrew F. The current now passes down the wire 1' to is, where it entersthe 'bellhelix 0. As soon, however, as this magnet works the armature t,the spring E makes contact with the screw P and allows the current toflow through Z m It P 019 7' sfto 0, instead of through 7r, 0, c, 1',.9, andf to (J, which latter is its course when passing through thehelix 0. Working intermittently in this manner, a continuous ringing ofthe bell Q, is secured as long as c and b are in contact. After acallthe spring N restores the beam eg, as before described.

It will be understood by the foregoing that whenever an impulse is sentalong the line, (open circuit,) or whenever the circuit is broken,(closed circuit,) connection is made at some one office on the line,which, if it be kept up long enough, will result in the ringing of thebell at that office or station; but if said contact be not maintained acertain appreciable timesay one or two secondsthe retardation of theshunt mechanism hereinbefore described will prevent the ringing of thebell.

The retardation of the shuntmechanism may be effected in other ways thanthe one described and shown, and therefore I do not limit myself to thatparticular device, but prefer it. A wheel or a train of two or moregears operating a fan, and thus utilizing the resistance of the air, maybe successfully employed.

I utilize for a calling local battery the transmitter-battery, which isalways at stations Where microphone-transmitters are used but anindependent local battery may be employed for this purpose, and onopen-circuit lines, for calling central office.

My invention differs from all others with which I am acquainted in thatthe discrimination between offices and the determination as to which oneshall be called is effected by a long or a short pulsation or break, asthe case may be, (and not by increasing, diminishing, or changing thepolarity of the current,) whereby I am enabled to use such strength ofcurrent as will insure the synchronism of the escapements.

Having fully described my invention, I claim as my own, and desire tosecure by Letters Patent, the following:

1. The combination of the local battery D, with circuit through (Z E c HFfG c and I) B, the electro-magnet E, armature K, beam 6 g,retracting-spring N, piston M, cylinder L, electro-magnet A, andescapement B I) G c, all constructed and operating substantially asdescribed.

2. The combination of the local battery D, with circuit through (Z E c IG i k 0 v r sfO c b B, the electro-magnet E, armature K, beam 6 g,retracting-spring N, piston M, cylinder L, electro magnet 0, andarmature Z, all constructed and operating substantially as described.

3. The combination of the cylinder L, piston M, retracting-spring N, andthe shunting device F H G I, operated by the battery D, electro-magnetE, armature K, and beam 0 g, with proper electrical connections,substantially as shown and described.

4. The call-bell proper, consisting, essentiall y, ofan electro-magnet,O, armature t, beam on, and bellQ, in combination with the battery D,having proper electrical connections, as shown and described, theelectro-magnet E, armature K, attached to the beam 0 g, theretracting-spring N, contact-spring I, contactpoint G, piston M, andcylinder L, all constructed and operating substantially as described.

5. The combination of the escapement B b O c, operated by theelectro-magnet A in the main line of a telegraph or telephone circuit,the local battery D, with electrical connections, as shown, theelectro-magnet E, with its armature K attached to the beam 0 g, theshunting device F l H G, operated by said beam 0 g, the retardingdevice, consisting, essentially, of the cylinder L and piston M, thelatter attached to the beam 0 g, the retractingspring N, and the tremblybell, consisting, essentially, of the electro-magnet O, armature t, andbeam m, all constructed and operating substantially as shown anddescribed.

6. The springs H I and contact-points F G, in combination with thecylinder L and piston M, all constructed and operatingsubstantially asshown and described.

MYRON LESLIE BAXTER.

Witnesses JAMES T. RICHARDSON, D. G. DIXON.

IIO

